JPH1171814A - Joint structure of steel-concrete composite construction part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a joint structure of a steel-concrete composite construction part which increases breaking resistance and has high toughness. SOLUTION: A joint structure has a steel baseplate 2 secured to the lower end of a steel structural member 1 and fixed in place by anchor bolts 4 embedded in a concrete structure 3. Clearance 10 is provided on the outer periphery of the structure immediately above the part in which each anchor bolt 4 is buried. The clearance 10 is formed when a through hole 2a bored in the base plate 2 for the anchor bolt 4 has its outer periphery removed in the form of a ring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joint structure of a steel / concrete composite structure, and more particularly to a steel / concrete composite structure for fixing a steel structural member such as a steel base plate with an anchor material embedded in concrete. It relates to a joint structure.

[0002]

2. Description of the Related Art For example, when a steel column or the like is fixed on a foundation concrete, a structure as shown in FIG.

In the joint structure shown in FIG. 1, a steel base plate 2 fixed to the lower end of a steel structural member 1 is fixed by anchor bolts 4 embedded in a concrete structure 3.
In this case, the base plate 2 is a concrete structure 2
Were tightly attached to each other by anchor bolts 4.

[0004] However, such a joint structure between a steel and concrete composite structure has the following technical problems.

[0005]

That is, when a horizontal shear force is applied to the joint structure shown in FIG. 8 as indicated by an arrow in FIG. 8 and the joint has sufficient strength. The shear strength of the joint is determined by the axial strength of the anchor bolt 4 or the shear strength of the concrete structure 3 in pushing out the anchor bolt 4.

In this case, since the concrete structure 3 is very brittle, it is desirable that the anchor bolt 4 be broken before the concrete structure 3 is broken.

Therefore, generally, the anchor bolt 4
Is set so that the axial strength of the concrete structure 3 is smaller than the punching shear strength of the concrete structure 3. However, FIG.
In the joint structure shown in (1), the base plate 2 is brought into close contact with the upper surface of the concrete structure 2, and these are tightly connected by the anchor bolts 4. Therefore, when a shear force is applied, the deformation of the anchor bolts 4 is restricted, Shear yield without passing through the deformed area, and then fractured.

[0008] When the anchor bolt 4 yields and breaks in this manner, the form leading to the breakage becomes brittle, and the ultimate displacement of the anchor bolt 4 is small, so that the structure cannot be expected to be tough.

The present invention has been made in view of such a conventional problem, and an object of the present invention is to provide a joint structure of a steel-concrete composite structure which has high fracture strength and high toughness. Is to provide.

[0010]

In order to achieve the above object, the present invention relates to a joint structure of a steel and concrete composite structure in which a steel structure is fixed by an anchor material embedded in a concrete structure. A clearance was provided on the outer periphery just above the material burial site. According to the joint structure configured as described above, since the clearance is provided on the outer periphery immediately above the embedded portion of the anchor material, when a shear force acts on the joint portion, deformation of the anchor material is allowed, and The brittle shear yielding and fracture of steel are avoided. In the joint structure of the present invention, the clearance may be filled or interposed with a low-elastic material or a low-strength material such as a low-strength mortar, an epoxy resin, or styrene foam.
According to this configuration, since the reaction force applied to the anchor member can be made smaller than that of concrete, bending deformation precedes and the maximum displacement amount leading to breakage increases. The joint structure of the present invention is a widely used general structure in which the steel structure includes a steel base plate mounted on a flat surface of the concrete structure, and the steel base plate is fixed by the anchor material. Applicable to configurations.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG.
1 shows a first embodiment of a joint structure of a steel and concrete composite structure according to the present invention.

In the following description, portions that are the same as or correspond to those of the conventional example shown in FIG. 8 are denoted by the same reference numerals, and portions different from the conventional example are denoted by new reference numerals.

The joint structure shown in FIG. 1 employs an anchor bolt (anchor material) in which a steel base plate 2 fixed to the lower end of a steel structural member 1 such as a column member is embedded in a concrete structure 3 as in the conventional example. ) Fixed at 4.

In this case, the base plate 2 is brought into close contact with the flat upper surface of the concrete structure 2, and these are fastened by the anchor bolts 4. The basic structure as such a joint structure is the conventional structure. Although the bonding structure is the same as that of the first embodiment, the bonding structure shown in this embodiment is significantly different in the points described below.

That is, in the case of the present embodiment, the clearance 10 is provided on the outer periphery immediately above the portion where the anchor bolt 4 is embedded. The clearance 10 is formed by annularly removing the outer peripheral portion on the lower end side of the insertion hole 2 a of the anchor bolt 4 formed in the base plate 2.

The clearance 10 has a depth approximately equal to the diameter of the bolt, and has an inner diameter approximately three times the shaft diameter of the anchor bolt 4. The clearance 10 is formed not only by cutting the base plate 10 in an annular shape but also by forming a slit-like groove or by reducing the inner peripheral side of the base plate 10 except for the outer peripheral portion. It may be formed in a shape.

When a shearing force in the horizontal direction acts on the joint structure thus configured, the clearance 10 is provided just above the embedded portion of the anchor bolt 4, so that the deformation of the anchor bolt 4 is allowed, and the anchor bolt 4 is allowed to deform. 4, brittle shear yielding and breaking are avoided.

As a result, as will be apparent from the test results described later, the loading point of the anchor bolt 4 in the shear direction rises, and the bending moment of the anchor bolt 4 under the same load becomes larger than in the conventional example. Bolt 4
Bending yields prior to shear failure, and fracture occurs after displacement progresses, so that a tough structure can be obtained.

FIG. 2 shows a second embodiment of the joint structure of the steel and concrete composite structure according to the present invention. The same or corresponding parts as those in the above embodiment are designated by the same reference numerals. A description thereof will be omitted, and only the characteristic points will be described below.

In the embodiment shown in the figure, an annular clearance 10 is provided just above the outer periphery of the embedded portion of the anchor bolt 4, similarly to the first embodiment. The clearance 10 is filled with a low-elasticity or low-strength material 12 such as a low-strength mortar, epoxy resin, or styrene foam.

According to the joint structure constructed as described above, in addition to the operation and effect of the first embodiment, since the low elastic material 12 is filled in the clearance 10, an anchor is provided in comparison with the conventional concrete. Since the reaction force on the outer periphery of the bolt 4 can be reduced, bending deformation precedes and the maximum displacement amount leading to breakage increases.

FIG. 3 shows a third embodiment of the joint structure of the steel and concrete composite structure according to the present invention. The same or corresponding parts as those in the above embodiment are designated by the same reference numerals. A description thereof will be omitted, and only the characteristic points will be described below.

In the embodiment shown in the figure, an annular clearance 10a is provided on the outer periphery of the anchor bolt 4 just above the embedding portion, similarly to the above embodiment. The clearance 10a of this embodiment is formed by annularly removing the outer periphery of the concrete structure 3 on the upper end side of the embedded portion of the anchor bolt 4 and is provided on the concrete structure 3 side.

[0024] In the joining structure thus configured,
The same operation and effects as those of the first embodiment can be obtained, and the same effects as those of the second embodiment can be obtained by filling the clearance 10a with a low-elastic material 12 such as low-strength mortar, epoxy resin, or styrene foam.

In the joining structure of this embodiment, a part of the clearance 10a is provided on the base plate 4 side, and the embodiment can be implemented in combination with the structure of the first embodiment.

FIG. 4 shows a fourth embodiment of the joint structure of the steel and concrete composite structure according to the present invention. The same or corresponding parts as those in the above embodiment are denoted by the same reference numerals. A description thereof will be omitted, and only the characteristic points will be described below.

In the joint structure shown in the figure, a low elastic material 14 is interposed between the upper surface of the concrete structure 3 and the lower surface of the base plate 2. The low elastic material 14 is a low strength mortar, epoxy resin, styrene foam, or the like having a lower strength than the concrete structure 3, and has a size to cover the entire surface of the base plate 2.

In the case of a low-strength mortar or epoxy resin, the low-elasticity material 14 is formed in advance in the form of a layer having a predetermined thickness on the upper surface side of the concrete structure 3 and the base plate 2 is formed on the upper side thereof. Put on, or
A clearance having a predetermined thickness is provided in advance on the upper surface side of the concrete structure 3, the base plate 2 is placed, and then the low elastic material 14 is injected.

In the case of styrofoam, a sheet-shaped material can be placed on the concrete structure 3 and interposed. According to the joining structure configured as described above,
The same effect as that of the second embodiment can be obtained without impairing the function of transmitting the vertical load of the steel structure 1 to the concrete structure 3 side.

FIGS. 5 and 6 show a shear tester used to confirm the operation and effect of the joint structure of the present invention. The shear tester shown in FIG. 1 includes a test table 16 on which the specimen A is mounted and fixed, and an axial force loading frame 18 fixed to one side of the test table 16.

The axial force loading frame 18 is provided with a steel rod 20 supported so as to be movable in the axial direction. Steel rod 2
An L-shaped bracket 22 is locked to one end of the steel bar 20, and a hydraulic jack 24 that pulls the steel bar 20 in the axial direction and an axial And a load cell 26 for measuring the amount of movement of the load cell.

The specimen A has a thickness of 200 mm and a thickness of 120 mm.
A concrete block a having a square shape of 0 mm, an anchor bolt b having a diameter of 27 mm, and a base plate piece c having a width of 200 mm are provided. An anchor bolt b made of mild steel is placed 150 mm at a position of 152.5 mm from the end face of the concrete block a. By embedding, the base plate piece c was fixed on the concrete block a.

The following six types of specimens A having such dimensions and shapes were prepared. Specimen 1: No clearance was provided immediately above the anchor bolt b buried portion. Specimen 2: A gap clearance of 20 mm provided around the anchor bolt b. Specimen 3: A gap clearance of 20 mm was provided around the anchor bolt b, and the clearance was 400 kg in strength.
Filled with grout of f / cm ² (low-strength mortar, the same applies hereinafter). Specimen 4: A gap clearance of 20 mm was provided around the anchor bolt b, and the clearance was set to a strength of 50 kgf.
/ Cm ² filled with grout. Specimen 5: A gap clearance of 40 mm was provided around the anchor bolt b, and the clearance was set to 50 kgf.
/ Cm ² filled with grout. Specimen 6: A gap clearance of 40 mm was provided around anchor bolt b, and the clearance was 600 kg in strength.
Filled with f / cm ² grout (Styrofoam). Each of the prepared specimens 1 to 6 was placed on the test table 16, the base plate piece c and the bracket 22 were connected with a bolt and a nut, and a tensile force was applied by a hydraulic jack 24 to measure the displacement of the anchor bolt b.

FIG. 7 shows the measurement results at this time.
As is clear from the test results shown in the figure, in the specimen 1 in which no clearance was provided immediately above the embedded portion of the anchor bolt b, the anchor bolt b was sheared and fractured by a tensile load of 12.87 tf. Displacement is about 10m
m.

On the other hand, in the specimen 2 in which the clearance is provided in the anchor bolt b, the magnitude of the shear fracture is almost the same, but the ultimate displacement of the anchor bolt b is about 3.5 times. .

A specimen 3 having a clearance provided in the anchor bolt b, and the clearance filled with grout.
In each of the samples Nos. 1 to 6, the shear breaking force was larger than that of the test piece 1, and in particular, the test piece 4 was about twice as small.

In the specimen 5, the ultimate displacement of the anchor bolt b is about nine times. As is clear from the test results, according to the joint structure of the present invention, the loading point in the shear direction of the anchor bolt b increases, and the bending moment of the anchor bolt b under the same load increases in comparison with the conventional example. In addition, it was proved that the anchor bolt b was fractured after the bending yield and the displacement proceeded ahead of the shear fracture, and that the structure became rich in toughness.

In the above embodiment, the structure in which the base plate 2 of the steel structure 1 is fixed to the concrete structure 3 with the anchor bolts 4 is exemplified. However, the embodiment of the present invention is not limited to this structure. For example, when the bracket provided on the steel structure 1 side is fixed to the concrete structure 3 or when the hollow member is fixed to the concrete structure 3, the present invention is applied to various steel and concrete composite structures. Can be.

[0039]

As described above in detail in the embodiments,
ADVANTAGE OF THE INVENTION According to the joining structure of the steel and concrete composite structure part concerning this invention, while avoiding brittle shear yielding and fracture of an anchor material, it can be set as the joining structure rich in toughness.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of a joint structure of a steel and concrete composite structure according to the present invention.

FIG. 2 is a sectional view showing a second embodiment of the joint structure of the steel and concrete composite structure according to the present invention.

FIG. 3 is a sectional view showing a third embodiment of the joint structure of a steel and concrete composite structure according to the present invention.

FIG. 4 is a sectional view showing a fourth embodiment of the joint structure of a steel and concrete composite structure according to the present invention.

FIG. 5 is a top view of a shear tester used for confirming the operation and effect of the joint structure between the steel and concrete composite structure according to the present invention.

FIG. 6 is a side view of a shearing tester used for confirming the operation and effect of the joint structure of the steel and concrete composite structure according to the present invention.

FIG. 7 is a graph showing test results obtained in a test using the same shear tester.

FIG. 8 is a cross-sectional view showing an example of a conventional joint structure of a steel and concrete composite structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steel structure 2 Base plate 3 Concrete structure 4 Anchor bolt 10, 10a Clearance 12, 14 Low elastic material

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tetsuya Shiozaki 2-3 Kandajicho, Chiyoda-ku, Tokyo Obayashi Corporation Tokyo head office

Claims (3)

[Claims] 1. A joint structure of a steel-concrete composite structure section in which a steel structure is fixed by an anchor material embedded in a concrete structure, wherein a clearance is provided on an outer periphery immediately above a portion where the anchor material is embedded. Steel-concrete composite structure. 2. The clearance is filled or interposed with a low-elastic material or a low-strength material such as low-strength mortar, epoxy resin, or styrene foam.
Joint structure of the steel and concrete composite structure described. 3. The steel structure according to claim 1, wherein the steel structure includes a steel base plate placed on a flat surface of the concrete structure, and the steel base plate is fixed by the anchor material. Joint structure of the steel and concrete composite structure described.